The present invention relates to methods for detecting hostile infiltration of protected perimeters and, more particularly to the use of encapsulated chemiluminescent materials to provide the detection capability.
U.S. troops operating in hostile territories such as South Vietnam constantly have been exposed to the risk of being surreptiously infiltrated by the enemy and significant injuries both personnel and equipment have resulted. If these problems are to be avoided, the enemy either must be quickly and positively identified at the moment the crossing or entry is being attempted or they must be readily distinguishable from our own forces once the infiltration has been achieved. This latter need is one that has been particularly apparent in our experiences in South Vietnam where the physical appearance of the enemy is practically indistinguishable from that of our allies.
In other comparable situations there has been a continuing need to detect enemy movements of either troops or equipment along well-known supply trails or across certain zones in which such movements presumably are contrary to mutual agreements. Such movements, of course, are attempted covertly under the cover of darkness so that normal reconnaisance, including aerial reconnaisance, has not been able to provide information that is particularly reliable or useful. Generally, it would be most desirable to provide a means for rendering these movements visually observable not only for intelligence purposes but also to permit the toops or equipment being moved to become immediate targets.
Another significant consideration that is the fact that any intruder who recognizes that he is `marked` by the luminescence will leave the area as promptly as possible without completing the intended mission. Such a psychological deterrent itself provides a considerable measure of protection.
Due to the seriousness of these and other similar problems, there has been considerable effort devoted to providing the requisite detection capability and various proposals have been attempted with some degree of success. Generally, however, the suggestions have involved relatively expensive and complicated instrumentation not too well suited for use in advance or outpost areas. Further, the proposals do not appear to provide a way of marking the infiltrating enemy or his mobile ordnance equipments so as to permit a ready identification as well as a ready target once they have moved across the protected area.
Although these considerations are of vital concern in military situations they also apply to a number of non-military circumstances. For example, such a detection capability can be used to advantage in crowd-control situations or in other situations where a particular area, building, or even a U.S. border is being protected against surreptitious crossing.